A major discovery of the past two decades in the field of neurosciences has been the elucidation of behavioural, neurobiological and cellular basis of learning and memory processes. The brain is an assembly of interrelated neural systems that regulates their owns and each other's activity in a dynamic, complex fashion. Morphological properties of central neurons have been very useful for the description of the functional characteristics. Learning is defined as the acquisition of information and skills, and subsequent retention of that information is called memory. Alzheimer's disease is the term used to describe a dementing disorder marked by certain brain changes, regardless of the age of onset. Accordingly, effect of a wide variety of pharmacological agents or brain lesion on cognitive behaviour have been studied and most validly interpreted as “enhancement or impairment” of learning and memory process. Learning and memory can be conceived as both psychological process as well as a change in synaptic neural connectivity. The development of scientifically validated models of ischemia induced-amnesia is vital to the analysis of the functional consequences of ischemic damage and to testing the behavioural efficacy of potentially therapeutic drugs. The role of medicinal plants in increasing the memory and acting as a brain tonic is still much underestimated. Besides this, certain oils have been found to be used as sedatives, central nervous system stimulants, adaptogens, bronchodilators, anti-stress and muscle relaxants (Singh et al, 2000). During late prenatal and early postnatal brain development, the cholinergic system in the central nervous system plays an important role in learning and memory function and that brain cholinergic hypo function causes dementia with symptoms such as memory loss and disorientation in cerebrovascular or alzheimers disease (Coyle et al 1983). Following cerebral ischemia, a reduction in the cerebral blood flow and blood oxygen occur. It has also been reported that hypoxia induces a reduction of memory and judgment that is associated with a decrease in acetylcholine synthesis (Gibson and Duffy, 1981). Principally, main characteristic of memory formation in animals, as well as in human being, is its progression from a short-lived labile form to a long-lasting stable form. During this period of consolidation, memory can be disrupted by administration of a wide variety of amnesia-inducing agents. Electro convulsive shock, hypothermia and hypoxia are non-invasive procedures that can render the animal unconscious, inducing retrograde amnesia through mechanisms correlated to the practical utility to the clinical drugs. The retrieval hypothesis postulates that amnesic agents disrupt memory recall rather than storage, as the effect of some agents diminish over time resulting in the reappearance of normal memory retention. The consolidation of information is mediated by limbic structures, with the hippocampal formation particularly playing a key role in memory processing. The major pathways have been proposed in the limbic system and cortical structures as being responsible for the neuronal interconnection of information processing. Drugs like amphetamine, caffeine-containing substances which have a stimulant activity on memory. Alzheimer's disease is not a normal part of aging—it is not something that inevitably happens in later life. Rather it is one of the dementing disorders, a group of brain diseases that lead to the loss of mental and physical functions. Alzheimer's disease is an exception, rather than rule, in old age. Alzheimer's disease or a related dementia afflicts only 5 to 6 percent of older people. Research indicates that 1 percent of the population aged 65-74 has severe dementia, increasing to 7 percent of those aged 75-84 and 25 percent of those 85 or older. The main risk factor for Alzheimer's disease is increased age. The rates of disease increase markedly with advancing age, with 25 percent of people over 85 suffering from Alzheimer's or other severe dementia. Some investigators, describing Alzheimer's may be due to heredity. The onset of Alzheimer's disease is usually very slow and gradual, seldom occurring before age 65. Over time, however, if follows a progressively more serious course. Among the symptoms that typically develop, none is unique to Alzheimer's disease at its various stages. It is therefore essential for suspicious changes to be thoroughly evaluated before they become inappropriately or negligently labeled Alzheimer's disease. Problem of memory, particularly recent or short-term memory, are common early in the course of disease. Microscopic brain tissue changes have been described in Alzheimer's disease since Alios Alzheimer first reported them in 1906. The two principal changes are senile or neuritic plaques (chemical deposits consisting of degenerating nerve cells combined with a form of protein called β amyloid) and neurofibrillary tangles (malformation within nerve cells). The plaques found in the brains of people with Alzheimer's disease appear to be made, in part, from protein molecules—amyloid precursor protein (APP)—that normally are essential components of the brain. Plaque are made when an enzyme snips APP apart at a specific place and then leaves the fragments β amyloid in the brain tissue where they come together in abnormal deposits. It has not as yet been definitely determined how neurofibrillary tangles are formed. As research on Alzheimer's disease progresses, scientists are describing other abnormal anatomical and chemical changes associated with the disease. These include nerve cell degeneration in the brain nucleus basal is of Meynert and reduced levels of the neurotransmitter acetylcholine in the brains of Alzheimer's disease victims. The clinical features of Alzheimer's disease, as opposed to the “tissue” changes, are three folds, firstly Dementia—significant loss of intellectual abilities such as memory capacity, severe enough to interfere with social or occupational functioning; secondly, Insidious onset of symptoms—subtly progressive and irreversible course with documented deterioration over time. Thirdly, Exclusion of all other specific causes of dementia by history, physical examination laboratory tests, psychometric and other studies. Research has discovered a protein, called Alzheimer's Disease Associated Protein (ADAP), in the autopsied brains of Alzheimer's patients. The proteins, which seems to appears only in people with Alzheimer's, is mainly concentrated in the cortex covering the front and side sections of the brain, regions involved in memory function. Researchers have found ADAP not only in the brain tissue but also in spinal fluid. Meanwhile, Alzheimer's disease is the most over diagnosed and misdiagnosed disorder of mental functioning in older adults. Part of the problem, already alluded to, is that many other disorders show symptoms that resemble those of Alzheimer's disease. The crucial difference, though, is that many of these disorders—unlike Alzheimer's disease—may be stopped, reversed, or cured with appropriate treatment. But they must be identified and not dismissed as Alzheimer's disease or senility. Condition that affect brain and result in intellectual, behavioural, and psychological dysfunction are referred to as “organic mental disorders”. These disorders represent a broad grouping of diseases and include Alzheimer's disease. Organic mental disorders that can cause clinical problem like those of Alzheimer's disease, but which might be reversible or controlled with proper diagnosis and treatment, include the several factors such as side effects of medications; substance abuse; metabolic disorders such, thyroid problems, nutritional deficiencies, anaemia etc; circulatory disorders such as heart problem, stroke; neurological disorders such normal-pressure hydrocephalus, multiple sclerosis, etc; infections like viral or fungal of the brain; Trauma, injuries to the head; toxic factors like carbon monoxide, methyl alcohol etc and Tumours, any type within the skull-whether originating or metastasising there of. In addition to organic mental disorders resulting from these diverse causes, other forms of mental dysfunction or mental health problem can also be confused with Alzheimer's disease. These form of condition are referred to as pseudodementia. Because of many other disorders that can be confused with Alzheimer's disease, a comprehensive clinical evaluation is essential to arrive at a correct diagnosis of symptoms that looks like those of Alzheimer's disease. Such an assessment should include at least three major components firstly a through general medical workup; secondly, a neurological examination, and thirdly, a psychiatric evaluation that may include psychological or psychometric testing. Alzheimer's disease has emerged as one of the great mysteries in modem day medicine, with a growing number of clues but still no answers as to its cause. The quest to uncover its cause has the air of a veritable whodunit saga. There are some theories, which tells about the cause of Alzheimer's disease. Though none of the leading theories about the genesis of Alzheimer's disease has resolved the mystery, each has led to certain intriguing findings that suggest further investigation is needed. Two critical crossroads reached in the approach to treatment for Alzheimer's disease were firstly, the recognition of Alzheimer's disease as a disorder distinct from the normal aging process; and secondly, the realization that, in developing therapeutic and social interventions for a major illness or disability, the concept of care can be as important as cure. In the Alzheimer's disease patient, depression or delusions can aggravate dysfunction. While Alzheimer's disease remains a mystery, with its cause and cure not yet found, there's considerable excitement and hope about the new findings that are unfolding in numerous research settings. There opened a new dimension in the treatment of neurodegenerative disease with a help of traditional medicine, which has proved to be effective in studying the deadly disease in animal model. Accordingly, studies shown that the herbal formulation(s) having the property of improving the memory and used in treatment of senile and pre senile dementia as a brain tonic and acting as a central antioxidant.